Various LNG mixtures primarily consist of methane and smaller amounts of other alkanes, which, despite their similarities, can exhibit different combustion phenomena. This study investigates the effect of LNG composition on ignition delay time and the likelihood of knocking. To this end, a C0-C4 kinetic model was developed based on a recently published methanol model, with the addition of C2-C4 sub-models. Eleven standard LNG mixtures were then simulated and studied under various experimental conditions at equivalence ratios of φ = 0.4 and 1.2. The results show good agreement with experimental data for high and intermediate temperatures (T ≥ 1000 K). The model outputs were also compared with the performance of two other well-established detailed models; the model developed in this study provides more successful predictions.

Finally, the formation pathway of combustion products was investigated using Rate of Production Analysis (ROPAD). As demonstrated, two distinct regimes—high-temperature and low-temperature—are identified for the combustion of each fuel component. At high temperatures, all fuel components undergo direct decomposition into small species and radicals, followed by combination with oxygen. At low temperatures, for methane, the formation of C2H6 from the methyl radical (CH3) is very significant, and the cascade hydrogen abstraction process is an effective mechanism in the continuation of the combustion pathway. This also applies to larger fuel components, rather than direct combination with oxygen.